Call of Cthulhu

Cthulhu Lives - the HP Lovecraft Historical Society
Cthulhu Lives is the website of the HP Lovecraft Historical Society, creators of the live action role playing game Cthulhu Lives.
http://www.cthulhulives.org/

PST Productions
Cthulhu LARP troupe in New Jersey. Site features photo and story gallery and previews of upcoming events.
http://members.tripod.com/~terrorpants/welcome.htm

Werebadger - Cthulhu/Lovecraftian LARPs
Lovecraftian-mythos live-action events - "Cthulhu LARP" is too constrictive a term. Group meets and plays in Scotland. Site features previews of upcoming events and photo album of things past.
http://www.werebadger.com/

Wraith
Set in World War II. Characters, rules, gallery, movies, spells and rules.
http://www.wraithcthulhu.com